Gatekeepers

Recently I have been wondering whether or not Rudy Guiliani could be nominated by the GOP as its Presidential candidate. His previous social views are the most often cited reason for his not being accepted. This of course raises a question in my mind: who are the gatekeepers in the Republican and Democratic Parties? What are the key issues to which a candidate must hew to the party orthodoxy in order to get nominated? I would ask for reader input on this, though I will submit my own list later. I also intend to ask several other bloggers what they think.

Update: So far, no responses. Somewhat disappointing, but I guess more incentive for me to create my own list.